The European landscape on allogeneic haematopoeietic cell transplantation in Chronic Lymphocytic Leukaemia between 2009-2019: a perspective from the Chronic Malignancies Working Party of the EBMT

Allogeneic transplantation (allo-HCT) is a curative treatment in CLL whose efficacy including the most severe forms had led to
the 2006 EBMT recommendations. The advent after 2014 of targeted therapies has revolutionized CLL management, allowing
prolonged control to patients who have failed immunochemotherapy and/or have TP53 alterations. We analysed the pre COVID
pandemic 2009–2019 EBMT registry. The yearly number of allo-HCT raised to 458 in 2011 yet dropped from 2013 onwards to an
apparent plateau above 100. Within the 10 countries who were under the EMA for drug approval and performed 83.5% of those
procedures, large initial differences were found but the annual number converged to 2–3 per 10 million inhabitants during the 3
most recent years suggesting that allo-HCT remains applied in selected patients. Long-term follow-up on targeted therapies
shows that most patients relapse, some early, with risk factors and resistance mechanisms being described. The treatment of
patients exposed to both BCL2 and BTK inhibitors and especially those with double refractory disease will become a challenge in
which allo-HCT remains a solid option in competition with emerging therapies that have yet to demonstrate their long-term
effectiveness.